Slag-forming welding electrode



' S. S. BERGH ETAL SLAG-FORMING WELDING ELECTRODE Feb. `24, 1959 FiledMay 16, 1955 weld ng elecTrode Tube .9v agnTm n l ng Slgmphase slgnorsto Wargns Aktiebolag, Vargon, Sweden, a Swedishompany y Apl'inaabi Mayis, 1955; sei-'ral No. 508,766 v 4claims priority, appliatia sweden July31, 195s 17 claims. (c1. 117`2os) This application isacontinuationin-part of our application Serial No.l380,862, filedSeptember 17,1953, Slag forming welding electrodes are Vofntwo types,namely those having a core of iron or iron alloy witha slag' formingcoating and those having a 1shell or tube of iron or `iron alloylledwiththe slag forming material. In both cases metals and erally arelincluded with the slag formingmaterial. lhe purpose of such metal ormetal alloy additionsis to alloy with the coreor shell metal and also toeffect deolgidation, Eor this purpose bothV pure metals 4and `metalalloys such asironv alloys e.; g. ferromnganese and ferrosiliconforleoxidation and. purenickel, ferrochromium and ferromolybdenumfc'Jr'alloying have been used. It :hsbee'n shown. tl'ratlthel commerciallon/,carbon ferrochrome with a chromium content of 65773% is verydiflcult to pnlverize which makes the resulting' po wder relativelyexpensive and limits its use Yin welding electrodes., i.

The object of 'thep'resent invention is to producerjless expensiveweldingl electrodes bythe use of powderof iron alloyI with alower'chromium content thantheplow, carbon arent alibi/S in powderedform gen- 1 ferrolchr'orne referred4 to above butnot asflow as ,thatn ofthe :well known steels, A. ,1 v g: n

`ironchro'inirnn alloys, in p state; of sigma phase,` having' l l 60%and the customary silicon and carbon contents have beerrioundrto lbelvery brittle prsapableoffbeing made brittle,` With pureiirori-febrornium necessary to` subject' rhein'to heat:v eatmenetedevelop brittlenessbit brittlen'esscanbe developed also by additions 0ffsttain elements su ca fase;Si,` A1,.M, W, V, Ti, Zr, Cb, 'I`,a, a nriliand M Y Veseelements may be added in sucllA substantial" ani nts"that',` Awithout noteworthy lossfof the `brittle property, otheralloying metals may be used-such .as.Cu, i persepare indifferentorwhich`counteract the sigma phase formation; A highcontent ofnickel'eormanganese `counteracts Cthe sigma .phase formation. "It4 is possible,khowever; to add nickel andmanganese in high quantitiesprovided thatoneor more ofthe aforesaid sigma promoting elementsispresent in asufcientquantity. u WAccording tothe invention,.saidsigmaphase formation isutilized in order to simplify the pulverization for manufacturing apowder to be used in welding electrodes and thereby lower the cost ofthe electrodes, and improve their quality. Some metals, e. g. nickel,cobalt and copper, are in pure form too soft to be ground into powder.When incorporated into a brittle sigma phase alloy, however, said softmetals may easily be ground together with the other elements containedin the alloy.

A phosphorus content of up to 1%, preferably 0.1% to 1%, a siliconcontent of up to 10%, preferably 1% to 10%, a molybdenum content of upto 10%, and a nickel content of 5% to 30% has been found suitable. Ithas been found that nickel may be replaced, wholly or partially, bymanganese. Thus, e. g. in an alloy of the kind stainless and heatresisting iron-'chromiumV llos/.S it generally isa chromium contentbetween about 30% and about Y `Co-and other metals, whichvcrentlybrittle, the 'desiredybrittleness can be imparted b'yeheattreatment at a temperature within the range 600,-8S 04C.-,Aswilllbeseen from -the above, .the vbrittle alloys, .the powdersotfwhichv are to be used in weldingelectrodes, depending upon .theircompositions, arey either brittle as they are formed without any specialembrittling treatment, orthey are 'cooled from the liquid state underconditions designed to develop brittleness i. e. by cooling more or lessslowly through-the range Ifrom 880 C. to 600 C. orY they are embrittledby being heated up for a sulficiently long time to within the range 600C. to 880 C., preferably about 800 C. and then cooled. The brittlealloys are then pulverized and incorporatedinto the weld-v ingelectrodes as cores or shells along with the slag forming materials nthe customary way.

Welding electrodes of the two types referred to'are illustrated in theaccompanying drawings in which: ....Fig. ..1 is .a-longitudinal sectionofa welding electrode havingfa solid core and aYslag-formingcoatingcontaining thesigma phasealloy, and Fi g 2 i?? longitudinal gestion 0f aweldirialelectrcde having `a shell or tube of the welding metal and aninner Slasffcrmina matins'. Contaiuiiigilhei s igralnhse alloy- Whensuchan electrode is used, the brittle alloy powder contained inthleshelbwill be reinelted and `simultaneously dilutedwith thecoremetal, e.-g. iron or nickeLjto'such annlentengt'thatgthe brttlenessdisappears, i. e. the compositionfoflthe resultingY alloy does not liewithin the sigma phrange. Y i If the electrode consistsof an iron ornickel tube anda. slag forming core containing an alloypowder in thesigma form, the same thing will occur when the electrode is used. Y

Qwing tothe ternary, quaternary or still more complexcompositiori ofsigma alloy, itsfmelting point is generally essentially lower comparedto that ofbrinary alloys. This isylof very greep-importance whenthe,alloyL is usedl for the manufacture Aof.,welding Aelectrodes andparticularly when the electrf'deh is to' contain powders'of metalsmelting atv high temperature, e. g. tungsten. When usingthe'electrode,the .powder, the core: material and possible iluxing agents are meltedin the arc,and the meltsare mixed in afshort time, a low. melting pointbeing of the greatest importance.: .f A N f Y v y l By practicing thefundamental idea of the invention it is, possible'. directly wh `ch whenused for welding electrodes of the types stated herein, `c'oiribine .inthemselves the properties ofA previously addeddeoxidants, e. g.ferrosilicon and ferromanganese,

A porated inthe weld and to improve its properties in onewayforanothenme. g. forincreasing the yresistance to corros'inorerosion, increasing the refractoryy properties, improving the hardness,tenacity, or the like. These properties areV obtained by suitablyadapting the alloying elements in the powder, while considering thegeneral rule that the composition shall be chosen so that a phasetransformation can be obtained, which effects the brittleness. Thus, bysuitably increasing the contents of silicon and manganese, it ispossible to obtain a desired deoxidizing effect without loss of moreexpensive alloying elements. Further, by suitably adapting the nobleralloying ingredients, such as chromium, nickel, molybdenum, copper,cobalt, tungsten and carbide forming elements such as titanium,vanadium, columbium, tantalum and zirconium, it is possible to obtainsuch a composition of to mea'mi'factlvireY uniform powders,V

with an unalloyed or alloyed core or case, on melting of the electrodethere is produced a weld of corrosion-resisting or refractory propertiesand with a content of alloying elements which is at least as high as inthe material, e. g. stainless steel, which is to be welded with saidelectrode, and consequently with at least as good properties as thismaterial. If, according to these directions, there is to be manufactureda powder for use in electrodes with a low alloyed or unalloyed core, andthe electrodes are to give a material in the Weld of the so-called 18/8-type, i. e. a material containing about 18% chromium and 8% nickelandpossibly also containing other metals which improve the properties, suchas manganese, molyb'- denum, copper, aluminum, tungsten and carbideforming elements and others, the alloy from-which the powder ismanufactured according to the invention shall contain chromium andnickel and other alloying elements in such a ratio that the weld obtainsthe desired composition. When welding, there is usually a loss ofchromium and, therefore, the ratio chromium to nickel should preferablybe somewhat higher in the sigma alloy than what is desired in the weld.

As examples of compositions of alloys of the kind referred to hereinwhich are brittle, the following may be cited.

Table Percent Per- Per- Per- Per- Per- Per- Per- 'Per- Per- Cr cent centcent cent cent cent cent cent;l cent N1 M0 Cu Al Si Ti Cb C0 P The restin each case consists of iron with the accessory elements or impuritiesusually contained therein.

As a rule it can be said that the necessity for heat treatment decreaseswith increasing contents of elements such as silicon, molybdenum,tungsten, titanium and vanadium.

The invention is not limited with respect to theV nature of the slagforming ingredient or the binder when the alloy powder is used in awelding electrodecoating. The coating may be acid, neutral or basic.`

We claim:

1. A welding electrode consisting essentially of a rod consistingprincipally of a metal selected from the group consisting of iron andnickel and a slag forming coating thereon, said coating` containing a,brittle sigma phase iron-chromium alloy having a chromium content ofE10-60%, the ingredients of the coating and the rod being capable offorming an alloy which does not contain sigma phase when the electrodeis used -for welding.

2. Electrode as defined in claim 1, in which the ironchromium alloy alsocontains nickel in quantity amounting to from to 30%. Y

3. Electrode as defined in claim 2, in which at least Y part of thenickel content is replaced by manganese, 1%

of manganese replacing about 0.5% of nickel.

4. Electrode as defined in claim 1, in which the ironchromium alloy alsocontains molybdenum in quantity up to 10%.

5. Electrode as defined in claim 1, in which the ironchromium alloy alsocontains silicon in quantity up to 10%.

6. Electrode as defined in claim 1, in which the iron? chromium alloyalso contains phosphorus in quantity up to 1%.

7. Electrode as defined in claim 1, in which thewiron chromium alloyconsists essentially of 58% of chromium, 2.0% of silicon and 40% ofiron.

8. Electrode as defined in claim l, in which the ironchromium alloyconsists essentially of 51% of chromium, 1.5% of silicon and 47.5% ofiron.

9. Electrode as defined in claim l, in which the ironchromium alloyconsists essentially of of chromium, 7% of nickel and 48% of iron.

l0. Electrode as defined in claim l, in which the ironchromium alloyconsists essentially of 47% of chromium, 12% of nickel and 41% of iron.

11. Electrode as defined in claim 1. in which the ironchromium alloyconsists essentially of 42% of chromium, 19% of nicke14% of silicon,0.2% of phosphorus and 34.8% of iron.

12. Electrode as defined in claim l, in which the ironchromium alloyconsists essentially of 47% of chromium, 19%V of nickel, 4% ofmolybdenum and 30% of iron.

13. Electrode as defined in claim l, in which the ironchromiumalloyconsists essentially of 43% of chromium, 19% of nickel, 5% ofmolybdenum, 4% of copper and 29% of iron.

14. Electrode as defined in claim l, in which the ironchromium alloyconsists essentially of 43% of chromium, 21% of nickel, 2% of titanium,4% of columbium and 30% of iron.

l5. Electrode as defined in claim l, in which the ironchromium alloyconsists essentially of 44% chromium, 18% of nickel, 6% of molybdenum,8% of copper and 24% of iron.

16. Electrode as defined in claim 1, in which the ironchromium alloyconsists essentially of 45% of chromium,

12% aluminium, 8% of silicon, 12% of cobalt and 23% of iron.

l7 Electrode as defined in claim l, in which the ironchromium alloyconsists essentially of 35% of chromium, 51% of titanium, 45% of cobaltand 15% of iron.

1. A WELDING ELECTRODE CONSISTING ESSENTIALLY OF A ROD CONSISTINGPRINCIPALLY OF A MENTAL SELECTED FROM THE GROUP CONSISTING OF IRON ANDNICKEL AND A SLAG FORMING COATING THEREON, SAID COATING CONTAINING ABRITTLE SIGMA PHASE IRON-CHROMIUM ALLOY HAVING A CHROMIUM CONTENT OF30-60%, THE INGREDIENTS OF THE COATING AND THE ROD BEING CAPABLE OFFORMING AN ALLOY WHICH DOES NOT CONTAIN SIGMA PHASE WHEN THE ELECTRODEIS USED FOR WELDING.